Waldo perceived the dismissal. "I may not know what I'm talkin' about," he said later, "but hell, them archaeologists don't know either. They're just guessin'."

One of the ﬁrst to guess was Noel Morss, an amateur archaeologist who named the Fremont in 1931, after digging sites in central Utah on the Fremont River. More than 70 years later, experts still struggle to come up with a list of distinctive cultural traits to differentiate the Fremont from their contemporaries to the south, the Anasazi. They know, for instance, that the Fremont created sophisticated rock art, leather moccasins rather than yucca sandals, and a particular kind of thin-walled gray pottery. These scholars believe that the Fremont homeland reached from Utah into Nevada, Idaho, Wyoming, and Colorado. Dwelling on the edge of the reliable growing season, where late-spring or early-fall frosts all too often ruined a whole year's crops, the Fremont never fully committed to a farming way of life. Many kept hunting and gathering as a fallback option, always ready to pack up and move on.

By a.d. 1350, the Fremont had largely disappeared from their homeland. No one knows what became of them. Perhaps some migrated east to the Great Plains and assimilated with nomads who hunted bison. Others may have been wiped out by the Ute, Shoshone, and Paiute, who might have surged into the Fremont heartland from the west as early as the 13th century. Perhaps many Fremont simply starved to death.

The most significant ruins in Range Creek are all high, inaccessible sites, many of them granaries. Greg Child, an expert mountaineer, Renee Barlow, and I worked our way into ones that even Waldo hadn't reached, becoming almost certainly the ﬁrst visitors in at least 700 years.

That the Fremont stored their grain on such severe cliffside ledges made perfect sense to Waldo. "It's like why you put your money in a bank," he said. "If you only got a little bit of corn, and everybody's hungry, you hide it away where other folks can't steal it."